Users:General FEM Analysis/Elements Reference/NURBS BRep Edge beam

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Coded and tested.


Element Type

This element formulation is based on geometric description. The center line of the beam is described by a NURBS curve within the parameter space of a NURBS surface. The beam is therefore autmatically coupled to the surface.

  • This element provides a geometrically nonlinear, isogeometric spatial beam within a NURBS surface.
  • Torsion without warping is included.
  • Twisting is dependent or dependent of the underlying NURBS surface.
  • Mass computation is implemented.

Degrees of Freedom

The element uses the translatoric degrees of freedom (Disp_X, Disp_Y, Disp_Z) at each control point. There is an optinial, additional, rotational degree of freedom (Rot_Tan), if the beam is twisted independently to the surface.

Parameter Description

Compulsory Parameters
Parameter Values, Default(*) Description
MAT EL-MAT int Linking to a material input block
INT_TYPE_NURBS_BREP_BEAM FULL, USER Control of integration type. If USER, the optional Parameter GAUSS_U (and GAUSS_V) has to be defined
AREA float area of the cross section of the beam
IY float moment of inertia
IZ float moment of inertia
IT float moment of inertia around the beam axis
TOR int beam twisting is independent of surface. The parameters 1 (yes) and 0 (no) are valid.
Optional Parameters
Parameter Values, Default(*) Description
GAUSS_U int Number of Gauss point per element. Must only to be defined when INT_TYPE_NURBS_BREP_BEAM = USER
AXIS AXIS float1 float2 float3 float4 Definition of the cross sectional principal axis. Second axis is perpendicual to first and tangent of the curve. float1 is the position on the curve and float - float4 the direction (x,y,z). Base vectors are normalized and linearly interpolated for postions inbetween the defined ones. Axes for start and end knot of the NURBS curve are mandatory. (not yet working!)

Example of a Complete Input Block

  AREA = 1.0
  IY = 1.0
  IZ = 1.0
  IT = 1.0
  TOR = 0 or 1
  GAUSS_U = 4

Element Loading

The NURBS_BRep_Edge_beam element is able to carry the following loads:

  • dead load
  • snow load
  • pressure load
  • moment load


Currently, no main benchmark file in the Carat++-repository is available.


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